Abstract Estimating elastic-plastic J-integral and Crack Opening Displacement (COD) for through-wall cracked pipes is important in Leak-Before-Break (LBB) assessment. For large-diameter piping, relevant through-wall crack length would be less than 20-30% of the circumference (the maximum 50%). In the case of Small Modular Reactors (SMR), however, many small-diameter piping may be used. For LBB analysis of such piping, it may be necessary to estimate J and COD for a longer crack. However, the applicability of existing solutions for estimating J and COD for long through-wall cracks is questionable. If not applicable, a new solution needs to be proposed. This paper firstly investigates whether existing reference stress based on J and COD estimation equations for a circumferential through-wall crack under bending can be applied to long through-wall cracks (defined by the crack length of up to 85% of the circumference). It is found that applicability depends on the mean radius-to-thickness ratio. Generally speaking, the difference between estimated and FE solutions tends to be larger for thicker pipes and for longer cracks. New solutions are thus proposed by modifying existing reference stress solutions.
Jeong et al. (Sun,) studied this question.
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